Heat treating furnace



June 20, 1967 M SCHER ET AL 3,326,542

HEAT TREATING FURNACE Filed Aug. 20, 1964 7 Sheets-Sheet l q HAROLD E. MESCHER WALTER E. HEYER BY Fw/Q M ATTORNEY June 20, 1967 H. E. MESCHER ET AL HEAT TREATING FURNACE Filed Aug. 20, 1964 7 Sheets-Sheet 2 EINVENTORS HAROLD E. MESCHER WALTER YE. HEYER BY fa /6f. M

ATTORNEY June 20, 1967 MESCHER ET AL 3,326,542

HEAT TREAT ING FURNACE 7 Sheets-Sheet 5 Filed Aug. 20, 1964 m mvamows fim aom amasca-zm WALTER EHEYEF? mwmhm A'F'TORNEY June 20, 1967 E H R ET AL 3,326,542

HEAT TREATING FURNACE 7 Sheets-Sheet 4 Filed Aug. 20, 1964 INVENTORS HAROLD E.MESCHER WALTER E.HEYER BY @4465. M

ATTORNEY June 20, 1967 MESCHER ET AL 3,326,542

HEAT TREATING FURNACE '7 Sheets-Sheet 5 Filed Aug. 20, 1964 INVENTORS HAROLD E.MESCHER WALTER E.HEYER ATTORNEY June 20, 1967 MESCHER ET AL 3,326,542

HEAT TREAT ING FURNACE Filed Aug. 20, 1964' '7 Sheets-Sheet '7 FIGB If IO IO I R I Q I I0 mu 0 I 00 I\ Rx (9 IO v v 1 0 LL N 9 u (D 33 3 INVENTORS LL w HAROLD E.MESCHER In 0 E M WALTER E.HEYER BY W6. M

ATTORNEY United States Patent 3,326,542 HEAT TREATING FURNACE Harold E. Mescher, Pico Rivera, and Walter E. Heyer,

Los Alamitos, Calif., msignors to Pacific Scientific Company, San Francisco, Calif, a corporation of California Filed Aug. 20, 1964, Ser. No. 390,819 11 Claims. (Cl. 266-5) This invention relates generally to heat treating furnaces, and the invention has reference, more particularly, to a novel furnace for heat treating long tubes or rods such as stainless steel tubing, the novel furnace being especially suitable for annealing tubing that may have lengths of anywhere from to 30 feet with diameters ranging from 1 /2" to 7".

Heretofore, such tubes have been either drawn or pushed through first a heating and then a cooling chamber in a continuous process at a relatively slow speed in order to complete the annealing operation, ranging from /4 to approximately 2' per minute. In using this prior method of annealing, the tubes are heated rather slowly and the transition between the heating and cooling chambers is delayed due to the slow movement of the tubes. This delay often causes excessive grain growth in the metal of the tubes, resulting in susceptibility to corrosion, which is highly objectionable.

The principal object of the present invention is to provide a novel furnace that is so constructed and arranged that tubes to be annealed or otherwise treated are purged and automatically inserted into the furnace heating chamber at a high rate of speed while under a controlled atmosphere, the tubes being heated rapidly within the heating chamber and retained the optimum time and then automatically transferred to the cooling section of the furnace quickly with practically no time spent in the transition from heating to cooling, whereby grain growth and grain structure is controlled as is desired with the heat-treated tubes leaving the furnace at substantially the same degree of brightness as they had on entering.

A feature of the present invention is to provide a novel furnace of the above character wherein the furnace casing proper consists of a hollow cylindrical body that is insulated interiorly and adapted to be heated from within by suitable heating elements, the tubes to be treated being initially inserted into cylindrical metallic or wire baskets, which baskets are then automatically pushed end-wise into sealed tubular purging chambers, the tubes of which are spaced mutually from one another and arranged with their longitudinal axes lying in a common cylindrical imaginary surface along which the chambers are adapted to move much like the barrels of a Gatling gun, suitable indexing means being provided for indexing or moving the purging chambers step by step so each chamber in succession is brought into alignment with the tubular interior of the furnace retort, means being provided for automatically sealing the purging chambers during purging and for pushing the loaded baskets from the purging chambers into the furnace in succession after the tubes to be treated have been purged with a desired gas such as hydrogen.

Another feature of the present invention is to provide a novel furnace of the above character wherein the furnace retort is provided at the end thereof remote from the purging chambers with a similar system of annularly disposed and mutually spaced cooling chambers which are also adapted to be turned and indexed so that baskets of treated tubes within the stationary furnace retort can be successively aligned with respective ones of said cooling chambers and whereupon means is provided for rapidly moving the tubes from the furnace mufiie into the respective cooling chambers to effect a rapid cooling of the tubes in a controlled atmosphere, the baskets of cooled tubes being automatically removable from the cooling chambers upon the cooling thereof, the whole operation of the furnace being automatic and continuous.

Another feature of the present invention is to provide a novel furnace of the above character wherein equipment is provided for preventing the turning or indexing of the purging chambers or of the cooling chambers, should a basket containing tubes to be treated be incompletely inserted into or removed from the furnace retort, as the case may be.

Another feature of the invention is to provide automatically operable sealing means for successively sealing off the furnace purge chamber and cooling chambers as work is inserted into or taken out of the furnace.

Other features and advantages of the invention will be apparent after a perusal of the following specification taken in connection with the accompanying drawings, wherein:

FIG. 1A is a partial perspective view of the present invention showing a portion of the furnace and the purging tubes with parts broken away, indexing means therefor and the pusher mechanism for pushing tubes to be treated into and out of the furnace retort.

FIG. 1B is a perspective view similar to 1A showing the remainder of the furnace with a portion of the furnace casing, loading and unloading trough, the cooling chambers and the indexing mechanism therefor.

FIG. 2 is an enlarged partial sectional view taken along line 22 of FIG. 1A, looking in the direction of the arrows.

FIG. 3 is a partial sectional view taken along the line 3-3 of FIG. 2.

FIG. 4 is an enlarged sectional view taken along the line 44 of FIG. 2.

FIG. 5 is a fragmentary sectional view taken along the line 5-5 of FIG. 1B illustrating the transfer mechanism for pushing the baskets from the loading and unloading trough into the purging chambers and from the cooling chambers onto such trough.

FIG. 6 is an enlarged fragmentary sectional view taken along line 6--6 of FIG. 5.

FIG. 7 is a fragmentary sectional view taken along line 7-7 of FIG. 1A, and illustrates details of the pusher mechanism.

FIG. 8 is a fragmentary sectional view taken along line 88 of FIG. 7.

FIG. 9 is a sectional view taken along line 9-9 of FIG. 7.

Similar characters of reference are used in the above figures to designate corresponding parts.

Referring now to the figures, reference numeral 1 designates the furnace casing, which is of a cylindrical shape and is interiorly insulated and shown provided with gas heating nozzles 2 for heating the interior of the furnace. Centrally within the furnace casing 1 there extends a cylindrical metallic tube retort 3 for receiving baskets 4 (see FIG. 1A) containing the tubes 5 to be heat treated. The furnace casing 1 is supported by a frame 6 which also supports a loading and unloading trough 7 having an outer hinged portion 7' upon which trough the baskets 4, filled with tubes to be heat treated, are manually placed prior to their automatic insertion into the purging tubular chambers or tubes 8. These purging tubular chambers are long, cylindrical chambers arranged with their longitudinal axes parallel and mutually spaced angularly with respect to each other about the longitudinal axis of a central common axial shaft 22 in the manner of the barrels of a Gatling gun, said chambers having their longitudinal axis lying in a common cylindrical imaginary surface along which the chambers are adapted to move. Looked at differently, the mutually spaced tubular chambers 8 are arranged in an annular row about the axis of shaft 22 being supported intermediate their lengths by discs 9 and surrounding bands 10 which roll upon rollers 11 mounted on a frame 12. The ends of tubular chambers or tubes 8 are secured within apertures in turnable discs 24 and 24' mounted on shaft 22.

The central tubular shaft 22 extends through discs 9 and has its ends turnably supported in stationary dies 23 and 23' (see FIGS. 1A and 3) supported from frame 6. The urging chambers 8 are adapted to be indexed, i.e., moved step by step by an indexing motor 13 acting through gearing 14, 14', which serves to align the purging chambers 8 consecutively in steps with the trough 7, 7', and also with the heated retort tube 3, these chambers turning about the longitudinal axis of shaft 22. To insure accurate alignment of the purging chambers with the heated retort 3, indexing locks 28 (see FIG. 2) are provided for automatically locking the purging chambers in desired aligned positions. The ends of the purging chambers or tubes 8 are arranged to be sealed by annular inflatable tubular seals 25 confined between sealed rings 30 and 30' carried by rotating discs 24 and 24' and stationary discs 23 and 23 so that a controlled atmosphere can be supplied to these tubes 8. Such an atmosphere may be a hydrogen atmosphere, for example, the hydrogen being supplied through port 72 into a stationary entrance tube 21 adapted to be aligned with successive tubes 8.

In advance of the trough 7, 7', there is provided a pneumatically operated circular gate 15 that is adapted to be raised and lowered by a piston movable within a pneumatic cylinder 17 having a piston rod 18 with enlarged tapered portion 18' (see FIG. 4) adapted to engage and raise the projection 15 of, the gate 15. Withthe piston rod 18 in its lowest position, shown in FIG. 4, a Wedgeshaped surface 19 on the projection 18 by pressing against stops 20, serves to press the gate 15 tightly against the entrance tube 21 and its circumferential seals 70 leading to an aligned tubular purging chamber 8. V

The stationary entrance tube 21 has its forward end provided with an inflatable gasket seal 27 which, when inflated, seals the aligned purge tube 8 with entrance tube 27 and away from the rest of the furnace. This purge tube 8 when aligned with the trough 7 and entrance tube 21 is also aligned at its outer foremost end with a closure plate 29 mounted on stationary disc 23' (see FIG. 3). Plate 29 also has an inflatable gasket seal 27 for sealing the purge tube away from the balance of the furnace. The gasket seals 27 are inflated before the gate 15 is opened so as to seal the purge chamber 8 aligned with trough 7 away from the remainder of the furnace so as not to contaminate the latter with air. An atmosphere outlet relief valve 73 is provided in circular closure plate 29 so as to allow air to escape as hydrogen enters through inlet 72. e I

The gate 15 is now opened and a basket 30 containing tubes or work to be heated or annealed and resting on trough 7, 7, is pushed by pusher carriage head 31 (see FIGS. 5 and 6) into the purge tube 8, passing through entrance tube 21. Head 31 is. carried by a hollow rod 32 longitudinally movable in a guide tube 33 that is carried by a loading and unloading carriage 34. This carriage has wheels 35 riding on rails 36 and 36 and is positively driven by a motor 37 acting through chain drive 38 to drive sprocket 39 over which a chain 40, fixed at its ends, passes. As motor 37 turns in the forward direction, sprocket 39, acting on stationary chain 40, drives carriage 34 to the left as viewed in FIG. 5, causing head 31 to push the basket 30 with work 5 therein into the aligned purge tube 8. Toward the end of the loading stroke of head 31 a lug 41 fixed on a chain 42 passing over idler sprocketsv 43 and 43 of carriage 34 will strike an adjustable stop projection 44 carried by frame 12 supporting the purge chambers 8 (see FIG. 4) stopping the forward movement of this lug, which will cause chain 42 to advance a projecting lug 45 thereon that is attached to rod 32 carrying the pusher head 31, whereby this head is advanced at greater speed until the basket 30 reaches the outer end of purge tube 8.

An automatic control system controlled from console 73, using limit switches, serves to advance the pusher head and carriage, and serves to retract these members after the basket 30 is fully inserted until the head 31 is exterior of the entrance tube 21. The gate 15 is now automatically closed, the tube 8 purged of air by use of suitable piping connected to port 72, and filled with a desired gas, such as hydrogen, which acts as a reducer, the air escaping through the valve 73, whereupon the purge chamber gasket seals 27 are deflated.

The indexing pins 28 are retracted by solenoids 71, whereupon the purge chambers or tubes 8 are indexed by motor 13 to bring a succeeding tube 8 into alignment with the trough 7, 7', at which time the index pins 28 are re-engaged. Also at this time another purge chamber 8' will become aligned with the furnace retort tube 3, this latter chamber 8 having already received a basket 30 filled with work to be treated. Actually, at this time, the retort 3 contains a basket 30 of work which has been heat treated in the furnace 1 and is ready to be quenched. In order to accomplish quenching and reloadingof the retort 3, a pusher mechanism 46 (see FIGS. 1A and 7) is employed. This mechanism comprises a pusher head 47 adapted to move into and through the purge tube 8 aligned with retort 3 and also enters the retort for positioning the new basket therein while causing the newly inserted basket to push the preceding heat treated basket of tubes out of the retort and into an aligned, water jacketed cooling chamber or tube 48. The pusher head 47 is carried by a movable rack 50, movable within pusher mechanism housing 46, and which is driven by a pinion 51 in turn drive from a pusher motor 52 through sprocket drive 53.

In pushing the treated work out into the cooling chamber 48 the forward end of the newly arriving basket 30 is pushed from the, aligned purge chamber 8 slightly beyond the furnace retort in order to move the finished work completely into the aligned cooling chamber 48, and this newly inserted basket has to be retracted somewhat for the furnace to functiomThis is accomplished by use of a spring biased pivoted latch 49 carried by a shaft 54 extending within a square tube 55 to which the rack is fixed. The outer end of shaft 54. is con-' nected by bell crank lever 56 pivoted at 56 on tube to a roller 57 riding on the inside of pusher housing 46. While the newlyv inserted basket 30 is pushing out the basket containing the previously treated work from the retort 3, roller 57 serves to hold latch 49 in its full line retracted position shown in FIG. 7 and out of engagement with the end of new basket 30 being pushed until this newly inserted basket is within a few feet of the end of its travel and the pushed basket is almostfully inserted into a cooling tube, whereupon roller 57 rides up. on a flared cam '58 allowing latch 49 to engage the end of basket 30 moving into the retort. At the end of the pusher heads travel with the previously heated basket 30 properly positioned in a cooling tube 48, the pusher mechanism reverses, due to automatic reversal of motor 52, causing the newly inserted basket to be retracted sufliciently to clear the rotating disc 60, of the cooling chamber structure (see FIG. 5) and associated parts, and. centers the now inserted basket within the furnace retort. The latch 49 serves to release the newly inserted basket at the time, due to roller 57 engaging and riding down cam 58 so that the pusher mechanism 46 can move to a fully retracted position outside of the purge tube structure.

The jacketed cooling chambers 48 are cooled with suitable cooling fluid such as water. Actually, the purging proximity to the hot furnace retort structure. Within the cooling chambers 48, the heated work is quickly quenched and those chambers are moved by the rotatable discs 60 and 60 While maintained in angularly spaced relation to each other about their common central axis of shaft 61. The discs 60 and 60' are turnably supported on the central shaft 61 and intermittently driven by an indexing motor 62 through sprocket gearing 63. Bands 10 and discs 9 serve to support the intermediate portions of cooling tubes 48 just as in the case of the purge tubes 8. Motor 62 is sequenced in its operation from console 72 with purge chamber indexing motor 13 so that the chambers 48 move successively in steps toward the loading and unloading trough 7-7.

The movement of both motors 13 and 62 are interlocked with the actual positioning of the baskets 30 within the purge chambers, furnace retort and cooling chambers by use of interlocking mechanism comprising pneumatic cylinders 64 (see FIG. 2) having actuating pistons 65 carrying feelers 66 at their lower ends, which feelers are automatically lowered and retracted prior to any turning movement of the purge chambers or cooling chambers. In case a basket is misaligned a feeler will contact the displaced basket and through relays prevent motion until its position is corrected.

With a quenched work basket 30 in a cooling chamber 48 aligned with the loading and unloading trough 7, 7', and assuming the index pins 28 are engaged, an inflatable gasket (see FIG. 5) seal 27 carried by exit chamber 67 of the cooling structure is inflated to seal the chamber 48 away from the remainder of the furnace to prevent outside atmosphere from contaminating the furnace. Exit chamber 67 is carried by cooling chamber stationary disc 23" similar to discs 23 and 23'. Gate 15' (see FIG. 5) similar to gate 15, is now opened by use of pneumatic cylinder 17', whereupon loading and unloading carriage motor 37 is operated in one direction to cause a latch 68 to enter the cooling chamber 48 and snap over and engage an end of the basket 30 therein, whereupon motor 37 automatically moves to pull the basket out of the chamber onto the trough 7, 7'. By energizing a pneumatic chamber 69 (see FIG. 6) the pivoted portion 7' of the trough is lowered and the basket can be moved thereoff and then taken from the furnace, the annealing or heat-treating operation being complete.

Actually in use, all of the purge chambers and most of the cooling chambers are loaded with work baskets most of the time during the automatic cyclic operation of the furnace, the purge chambers and cooling chambers moving in intermittent steps.

When using hydrogen, which serves as a reducing gas to keep surfaces clean, it is necessary to purge the entrance chamber 21 and exit chamber 67 with nitrogen gas, for example, just as the gates 15 and 15' are opened to prevent possible explosions.

In use, the novel furnace operates continuously, in steps, its various operations being initiated automatically from a control console 73.

Owing to the rapid movement of the work tubes from the purge chambers into the furnace retort, and from this retort to the cooling chambers under controlled atmosphere conditions, the work leaves the furnace substantially as bright as when it entered, not only on the outside, but also on the inside of the tubes. The only non-automatic work required is to load the baskets onto and take them off of the loading and unloading trough 7, 7'.

Since many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a heat-treating furnace, a longitudinally extending furnace retort, a purge chamber structure comprising a plurality of mutually spaced intermittently rotatable tubular purge chambers positioned adjacent one end of said retort and arranged in an annular row about a common central axis, a plurality of mutually spaced intermittently rotatable tubular cooling chambers positioned adjacent the other end of said retort and also arrangedin an annular row about a common central axis, a loading and unloading trough, said purge chambers being successively aligned with one end of said trough for loading work into said purge chambers in steps and being successively aligned with said furnace retort for passing work from said purge chambers into said retort in steps, said cooling chambers being successively aligned with said furnace retort for receiving work from said retort in steps and being successively aligned with the otherend of said trough for unloading finished work onto said trough in steps.

2. A heat treating furnace as defined in claim 1 comprising pusher mechanism for pushing new work from said trough into said purge chambers and for pulling completed work from said cooling chambers onto said trough.

3. A heat treating furnace as defined in claim 2 comprising an additional pusher mechanism for pushing purged work from said purging chambers into said furnace retort and for pushing heated work from said retort into said cooling chambers.

4. A heat treating furnace as defined in claim 3 having inflatable seals on said purging and cooling structures for maintaining a desired controlled atmosphere within said furnace.

5. A heat treating furnace as defined in claim 4 wherein feeling mechanism is employed for detecting any misplacement of work within said furnace.

6. A heat treating furnace comprising a centrally located, relatively long furnace tube, a tubular retort therewithin, intermittently rotatable tubular purging and cooling chamber structures located at opposite ends of said furnace tube and arranged to have the ends of their chambers adjacent said furnace tube intermittently aligned re-- spectively with the respective ends of said retort, loading mechanism for inserting work into the ends of said purging chambers adjacent said furnace tube in succession and for removing work from said cooling chambers in succession, and sealing means for maintaining a controlled atmosphere within said furnace retort and said purging and cooling chamber structures.

7. A heat treating furnace as defined in claim 6 having pusher mechanism for pushing purged work from said purging chambers in succession into said retort and for concurrently pushing heat treated work from said retort into said cooling chambers.

8. A heat treating furnace as defined in claim 7 wherein means is provided for accurately indexing said purging and cooling chambers, said means including retractable indexing pins for engaging said purging chamber and cooling chamber structures.

9. A heat treating furnace as defined in claim 8 wherein sensing mechanism is employed for insuring that work within said furnace is properly positioned within said retort and said purging and cooling chamber structures to enable relative movement between said structures and said retort.

10. In a heat treating furnace, a retort, a purge chamber structure comprising a plurality of mutually spaced purge chambers arranged in an annular row intermittently rotatable so as to bring each purge chamber in succession into alignment with one end of said retort, a cooling chamber structure at the opposite end of said retort, a pusher mechanism positioned at the end of said purge chamber structure remote from said retort for alignment with a purge chamber aligned with said retort, said pusher mechanism comprising a pusher tube, a pusher rack within said tube, a pusher head carried by said rack, a pivoted latch mounted on saidpusher'head, cam means for actuating said latch, and means for reciprocating said pusher rack, whereby movement of said pusher rack in one direction causes saidhead to push work to be treated from the aligned purge tube into said retort, said work entering slightly into said cooling chamber structure, movement of said pusher rack in the reverse direction causing said cam means to actuate said latch to retract the work to be treated somewhat to place it entirely within said retort.

11. A heat treating furnace as defined in claim 10 wherein said cooling chamber structure comprises a plurality of mutually spaced cooling chambers arranged in an annular row and intermittently moved so that successive cooling chambers are aligne'd successively with said retort, said pusher mechanism servingto cause the work to be treated to push work previously heated from said retort into a cooling chamber While inserting the new work into said retort.

References Cited UNITED STATES PATENTS 2,667,999 2/1954 Vore 2636 X JOHN F. CAMPBELL, Primary Examiner.

ROBERT F. DROPKIN, Assistant Examiner. 

1. IN A HEAT-TREATING FURNACE, A LONGITUDINALLY EXTENDING FURNACE RETORT, A PURGE CHAMBER STRUCTURE COMPRISING A TING BEING FABRICATED FROM REFRACTORIES SELECTED FROM THE TUBULAR PURGE CHAMBERS POSITIONED ADJACENT ONE END OF SAID RETORT AND ARRANGED IN AN ANNULAR ROW ABOUT A COMMON CENTRAL AXIS, A PLURALITY OF MUTUALLY SPACED INTERMITTENTLY ROTATABLE TUBULAR COOLING CHAMBERS POSITIONED ADJACENT THE OTHER END OF SAID RETORT AND ALSO ARRANGED IN AN ANNULAR ROW ABOUT A COMMON CENTRAL AXIS, A LOADING AND UNLOADING TROUGH, SAID PURGE CHAMBERS BEING SUCCESSIVELY ALIGNED WITH ONE END OF SAID TROUGH FOR LOADING WORK INTO SAID PURGE CHAMBERS IN STEPS AND BEING SUCCESSIVELY ALIGNED WITH SAID FURNACE RETORT FOR PASSING WORK FROM SAID PURGE CHAMBERS INTO SAID RETORT IN STEPS, SAID COOLING CHAMBERS BEING SUCCESSIVELY ALIGNED NACE RETORT FOR RECEIVING WORK FROM SAID RETORT IN STEPS AND BEING SUCCESSIVELY ALIGNED WITH THE OTHER END OF SAID TROUGH FOR UNLOADING FINISHED WORK ONTO SAID TROUGH IN STEPS. 